Abstract: Briefed in the article is the application of the square steel tube both at home and abroad, focusing on the application of such tube in the construction sector. Also analyzed roughly is the prospect of application of the same tube in domestic construction sector. In addition, several manufacturing processes of the seamless steel square tube and their features are described, including the cold-bending formation process, 4-high hot-rolling formation process and 2-high hot-rolling formation process.